As I mention, the backup is running properly before (include the system state) can successfully be backup. However, the last two month, the backup exec begin fail to backup the system state with unknown reason. I have already try to reboot both server and test only backup the remote system state, but after it backup 40~50 mb data, the job automatic cancel with the access denied message.
p.s. I have try to use ntbackup to backup the system state and it can success. And the user account that use by the BE is already the domain administrator.